How easy would it be to plant a garden if the seeds buried themselves? That's exactly what the seeds of Erodium cicutarium, a close relative of the Geranium genus, do. Adults of the species, which is considered an invasive menace in several U.S. states, launch the seeds as far as half a meter and
once the seeds hit the soil, they drill themselves into it. In a paper published
today in the Journal of Experimental Biology, researchers have for the first time captured the seeds' self-drilling behavior on camera. It turns
out that while the plant's fruit grows and ripens, the seed remains moist and straight. But when the seed dries out, a straplike beam running the
length of the seed, called an awn, begins to contract and coil until, finally, the seed springs away from the plant. The awn continues to coil as it
hits the soil, drilling itself in. "It's basically like a Slinky that's been pulled straight, then let go," says Dennis Evangelista, a biology grad
student at the University of California, Berkeley, and one of the paper's co-authors. As the dew point rises and wanes over the next several days, the
seed continues to twist itself into the soil until it's deep enough to begin the next generation of drillers.
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